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HAProxy Load Balancer: free, open source, reliable

HAProxy, which stands for High Availability Proxy, is a popular open source software TCP/HTTP Load Balancer and proxying solution. HAProxy is free, open source software that provides a high availability load balancer and proxy server for TCP and HTTP-based applications that spreads requests across multiple servers. It is a TCP/HTTP reverse proxy which is particularly suited for high availability environments. It features connection persistence through HTTP cookies, load balancing, header addition, modification, deletion both ways. It has request blocking capabilities and provides interface to display server status.
Written in: C

Download HAProxy: Source Code

License: OpenSource HAPROXY's license (GPL compatible)

Project Website: haproxy.org

Documentation: haproxy.org/#docs

Project Goals
  • It offers high availability, load balancing, and proxying for TCP and HTTP-based applications.
  • It is particularly suited for very high traffic web sites and powers quite a number of the world's most visited ones.
  • To be de-facto standard opensource load balancer, being shipped with most mainstream Linux distributions, and often deployed by default in cloud platforms.
Project Features
  • Layer 4 (TCP) and Layer 7 (HTTP) load balancing
  • URL rewriting
  • Rate limiting
  • SSL/TLS termination
  • Gzip compression
  • Proxy Protocol support
  • Health checking
  • Connection and HTTP message logging
Project Design and Security
  • It offers the building blocks to create a strong, layered defense against DDoS, malicious bot traffic, vulnerability scanners and more.
  • HTTP normalizer: when configured to process HTTP traffic, only valid complete requests are passed. This protects against a lot of protocol-based attacks.
  • HTTP fixing tool : it can modify / fix / add / remove / rewrite the URL or any request or response header. This helps fixing interoperability issues in complex environments.
  • Observation point for network troubleshooting : due to the precision of the information reported in logs, it is often used to narrow down some network-related issues.

Sample Configuration
# Sample Configuration for HAProxy @ /etc/haproxy/haproxy.cfg

	log local0 debug
	maxconn	1024
	chroot 	/var/haproxy
	uid		604
	gid		604
	pidfile	/var/run/haproxy.pid

	log		global
	mode	http
	option	httplog
	option	dontlognull
	option	redispatch
	retries	3
	maxconn	2000

frontend haproxy
	bind 			*:80
	default_backend	httpd

backend httpd
	option			forwardfor
	http-request	set-header X-Forwarded-For %[src]
	balance			roundrobin
	server			www check
	server			www check